Demand for high-dielectric memory devices or ferroelectric memory devices which use a high-dielectric capacitor or a ferroelectric capacitor as the semiconductor memory has been growing in recent years.
A high-dielectric capacitor is that which uses a high-dielectric material such as BSTO ((Ba, Sr) TiO.sub.3) for the dielectric film and forms the cell capacitor of the memory cell in a DRAM (Dynamic Random Access Memory).
Also, by using a ferroelectric material such as PZT (Pb (Zr, Ti) O.sub.3) for the dielectric film and forming a cell capacitor, a memory cell of FRAM (Ferroelectric Random Access Memory) which is a nonvolatile storage element that uses the residual polarization characteristic thereof is composed.
However, securing the capacitor area of the memory cell is becoming difficult as the enhancement in the integration progresses in, for example, DRAM. In order to deal with this problem, examinations have been made such as making the capacitor structure three-dimensional or using a material of high dielectric constant for the dielectric film.
The high-dielectric capacitor used in a memory cell uses, for example, a Pt/TiN/Ti or an Ir/TiN/Ti structure in which bottom electrode 38 composed of Pt or Ir is laminated on barrier metal layer 39 composed of TiN layer and Ti adhesive layer for preventing the diffusion of the electrode compositional components; high-dielectric thin film 40 such as BSTO, etc., is formed on this laminated body according to the sputtering method or the deposition method of an electron-beam heating system; and top electrode 37 composed of Pt or Ir is formed into an approximately identical pattern as shown in FIG. 6.
In this type of dielectric capacitor (Cap) and memory cell (M-Cel) shown in FIG. 6, the electrode of the capacitor is mainly formed by sputtering or vapor depositing platinum (Pt) when using BSTO for the dielectric film 12.
However, as a result of having examined said platinum electrode, the present inventors found that the surface of said Pt bottom electrode 38 manifests a rough surface with many pointed convex parts 38a existing in an island shape as shown in FIG. 14. This is due to the fact that particles of Pt adhere in a conical shape from sputtering or vapor deposition.
In a dielectric capacitor, insulation property is one important performance but it was found that in the aforementioned structure, the leakage current is great and becomes the major defect for influencing the performance of the dielectric memory device. When the leakage current increases, the charge-storage state of the dielectric memory device fluctuates and erroneous operation or failure in the memory function may occur.
The objective of the present invention is to provide a high-performance dielectric capacitor and a dielectric memory device which greatly reduces or does not generate leakage current and a method for manufacturing these with favorable reproducibility.